Thermal power generation plants remain one of the main means for generation of electricity, in e.g. fossil fuelled plants and nuclear plants. It is estimated that up to 8 to 10 percent of its generated power is consumed for its internal electric consumption in so-called auxiliary loads. The auxiliary loads comprise e.g. fans, compressors, pumps, that are necessary for the operation of the plant, performing tasks such as feeding water, feeding air for combustion, transport of fuel and waste, etc.
In a typical large scale plant, the most energy consuming loads are fan, pump and compressor drives, typically rated 1-5 MW and consuming 5 to 40 GWh per year. In view of demands for energy efficiency it would be beneficial to provide more power with the same CO2 emission. Consequently, it is desirable to reduce the power consumption of the auxiliary loads. Not only reduction of active power consumption would be beneficial; it would also be beneficial to avoid distributing reactive power consumption over the whole plant, making reactive power local, and thus reducing distribution losses in cables.